So I've started the "Blood and Ice" quest on Windhelm.Everything was fine until I followed Viola Giordano on Hjerim(the house),when she entered she suddenly froze in one place and whatever I do she wont move a inch,so I'm unable to finish the quest.Any ideas??

Are you the Unofficial Patches? If not, why?

Not absolutely sure whether USKP will help but Blood On The Ice is notoriously buggy quest and USKP will eliminate at least most of them.

I download it the Unofficial Patches but nothing.Oh boy and the thing is I bought Hjerim and now I won't be able even to buy furniture because I have to finish the quest first.

But if you guys have any ideas do say,I'm all ears.

Remember to get he Unofficial Patches for any DLC have as well. Remember the load order!

Did load the last save when you retried? Try loading a save from before starting the quest. The entire progress of quest may have glitched irreversibly so it's necessary to restart the quest. Load earlier save.

I agree but unfortunately I deleted my earlier saves.

Well, in that case there might not be anything else to do to save the situation. It is very important to keep decent amount of earlier saves for things just like this.

Even with Unofficial Patches some things can still go wrong.